Recirculation underjet coking retort oven



J. VAN AcKl-:REN

RECIRCULATION UNDERJET COKING RETORT OVEN Filed July 14, 1951 July 16, 1957 6 Sheets-Sheet l July 16, 1957 J. VAN ACKEREN RECIRCULATION UNDERJET COKING RETORT OVEN Filed Ju]y 14, 1951 5 Sheets-Sheet 2 m, .WAR

July 16, 1957 J. VAN ACKEREN RECIRCULATION UNDERJET comm; RETORT OVEN 6 sheets-sheet 5 Filed July 14, 1951 F/ci. 4

I NI "EN TOR. dosf'/f mw HCKEEN BY fw wm July 16, 1957 J. VAN ACKEREN RECIRCULATION UNDERJET COKING RETORT OVEN e sheets-sheet 4 Filed July 14, 1951 652' @4 3o 3o 5 63x?, .3.4 I

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INVENTOR.

July 16, 1957 J. VAN AQKEREN RECIRCULATION UNDERJET COKING RETORT OVEN Filed July 14, 1951 .6 Sheets-Sheet 5 o l /UN G /A/ F LIL,

f INVENTOR. F/G' 8 JOSEPH wmc/eew July 16, 1957 .1.-vAN ACKEREN 2,799,632

RECIRCULATION UNDERJET COKING RETORT OVENv L JNVENToR.

dosfpf/ maga/Eef# Joseph `Van Ackeren,

RECIRCULATION UNDERJET` CQKING RETORT OVEN Pittsburgh, Pa., assigner to Kop- ,pers Company, Inc., a-corporation-of Delaware Application Julyltl, 19 S,A1,: Serial No. 236,808

acclaim. Av(mm- (142) V,This invention relates v in general to t improvements in n.crtins retort cvcn batteries, .and more particularly `tc improvements in the construction and operation of cokng-retort-ovens of Ithe type described and claimed inmy Patents; 2,306,678 4of rDecember 2 9, 1942 and '2,507,554 .ofMay 1 6, 19,50.

YAn o .bjec :t of the invention isvto provideleakage-proof plates interposed in a horizontal plane ingthe masonry be- @tweenthe bottoms lof the -regeneraton sole fflues ori channels, and thewaste gas recirculation duct beneath the regnrlaff S916 :.Chanllels, `which recirculation =duct connects onand olf richygasrisersv tovfeedwastegas from ,the oil `combustion uesinto .admixture :with rich lgas fPriOttQ fitsilistharsc into fcnccmbustcn ues, in .ovens lc f` t l1 e aforesaid type. These plates 1are provided here to further,insurefthe absenceof, leakage from the regeneratorf sole ues into the recirulatinguct.

A.A further Aobject of -the iinvention is toprovide an under- .jet coleoven structure-in which the recirculation duct, when l ocated in the oven m at,and the rich gas nozzle Of my. aforesaid*patcntgstwcturc, crean l interconnected or `keyed with the silica .lbrickwork, for `simultaneous movement of-thern together, in unison with saidsilica brickwork, relative tothe-oven-matand the `Sole channels, as asingle structural unitary whole, to-maintain the recirculation ,ductas well .-as the nozzle, vand the venturi throat, when employed, in alignmentwith-eachotherand lwith the rest of f the underjets, v,as thesillicabrickworktmoves diiferentially relative to the concerete `vof the matand to the .clay of the briclcotthe sole channels.

Said, coking retort ovensof my aforesaid'patents are characterized by .wast e gas recirculation ,ducts-beneath. `the sole tcharinelsv ofregeneratQrs, which recirculation ducts connect fon .and o underjettlucta or risers 4forgfeed of waste gas from the off to the ou rich gasrisers 4that.feedvertical.combustion fines ofgthe heatingwalls yalongside the coling chambers.

ln operation,.the onand j-o .richi.tgasf.ri sers,or un- .derjet ducts Aare fed in alternation withy rich gas, such as coke oven gas, in .calibratedlamounts whicharesintroducedin lthe f ormppfga jet hyfnozzlesat thejuncture ,of therecirculation 4duct v'v viththe o r1.and foi,rich gas risers.

The .jet ,action-of the calibrated gas inducesa flow -of waste gas from. the o riser throughfthe recirculation duct intothe on riser, in amounts proportionate to dilutethe richgas to produce-.elongation of its ame of combustion in' the heating -wall combustion ilues, and thus effect relativelyfuniformfthermal conditions 4inthe heating walls similarftoEthat obtainable .in -underlring with regenerativelylpreheated lean, gas,.. such as producer Vgas andtblastfurnace gas.

In addition,.ttl 1e coke oven batteries of saidtpatents .are bniltof-refractory shapes, and so ,the ,structure Vin `the region of the bottom of the sole channelsfoftheregenerators ,andthe reircnlation d uctcrequire joints fforiexpansion.

2,799,632 Patented July 16, 1957 -As .a consequence it is possible, in the-course ofthe life Kofvl a 1tte ri =.s ofcokeovens .so constituted, that small amounts of..air orvwaste gas might be drawn mto l the recirculating ducts `from the adjacent sole lines, disturbing theuniforrnity oftheating achieved by the waste gaslrecir- -found -suitable as disclosed in my aforesaid v"Patent 2,507,554. However, itis s tillpossible with that. construction for vsome leakage to. occur in time aroundv the .rnetalliner and at its ends, ifv the expansion joint packing wearsor fails,v ory the mortar joints zdevelop ssures {Thev present inventionis directed .to .providing amore simple, more eifective, and moreeconomical solution-of lthe problems that may arise inthe subsequent .operations of ycoke ovens lof the waste gas recirculation typeandfthe .accomplishing `ofzthis in a manner that .avoids the disadvantages above discussed.

Accordingly, the present invention provides 4for the purpose metal plates interposed in a. horizontal plane in thetbrickwork between the .bottoms of the sole channels, `a r id the-tops ofthe recirculation ducts that are Vbeneath the sole. channels,rand thatrconnect-fon andv off rich sgas riserslorunderjettducts, to feedtwo sets of ues, operablein alternation for inow combustion and simultaneous Aoutowof combustion products, as inthe case of haria-pin, `or other. types of heating llue systems, and more particularly cross-over 'flue Ainterconnected vertical combustion ue heating systems, as in my aforesaid patents.

nlrcferably these metal plates arerof stainless steel, for

example theconventional No. `24 gauge, typ@ 3 02, and extend across the Widthfof the regenerators in tothe re- ,generator division walls to scalfoif the sole channels Iand the. joints for. expansion of the surrounding structureA relative to them lfrom the recirculation ducts.

The plates preferably lie inthe j oint between the sole f lue bottomsvand the tops ofthe recirculation ducts. .fThese plates .act .to interceptV joints to insure the absence ofaleakage from the sole flues into the lrecirculation iuc t s, `and'into the rich gasriser ducts.

iSuch4 stainlesssteel plates will withstand the temperatures that -existlin the recited specic location 'for said plates in such coke oven batteries, and will not deteriorate throughout the `norrnallife of such batteries, being sufliciently heat-andvabrasion resistantunder ythe expected normal service conditions, since like plates have been used ,in suchbatteries at higher levels to prevent ,leakage between onando if regenerators, and between fon regeneratorsand "o sole ues for olf regenerators.

E1n one `form, the invention is incorporated ina coke oven .battery constructed -in accordance with my ,aforesaidlU. S. Patent No. 2,507,554. As there shown, the recirculation duct is incorporated in thebrickwork immediatelyover the concrete oven mat between the `same and the floors of the regenerator sole channelsjthat-are immediately above. While the metal liner and its lining of iireclay :for the inside of .the recirculation Aducts may alsobe used as an auxiliary safeguard in connection withthe recirculation duct, when employing the metal leakage-proof plates of the presentinvention between the top ofthe recirculation duct andthe iloor of the `regencrator s ole channels, preferably the inner rneta'llic liner, and its iireclay lining is omitted whenemploying the joint intercepting metal plates in the .location they are employed in accordance with the presently preferred embodiment, since the plates as used herein prevent. flow of leakage around them, and makeunnecessary thellse of the expansion joint packing as in myprior construction. l

In another form, the invention here is employed with the metal leakage-proof plates laid directly horizontally along the top surface of the concrete oven mat. In this form, the recirculation duct is located within the concrete mat of the oven as in my aforesaid Patent 2,306,678.

In this embodiment the regenerator sole-ue floor is laid directly on the concrete oven pad, with the metal joint-intercepting plate disposed in a horizontal plane in between, thus eliminating the silica brick till under the sole flue as is required when the recirculation duct is built in the brickwork immediately over the concrete pad, as illustrated in the first described and preferred embodiment of this invention which incorporates those features of my aforesaid Patent 2,507,554.

This second embodiment of the invention also permits employing the same height of regenerative area with a decrease in the overall height of an oven battery, thus attaining the same heating effect in an oven battery but with a lower overall height.

In these two forms of the invention, the concrete mat and the clay brick of the sole ilues expand at the same rate, whereas the silica of the regenerator division and pillar walls expands at a greater rate as compared with the clay and concrete, and so a concrete curb or equivalent is provided at each end of the sole flue to prevent the clay brick of the flue from being carried out with the silica as the brickwork is heated. In both cases the metal joint intercepting plate prevents leakage from the sole flue to the recirculation ducts by sealing off the open joints of the sole flues from the area of the recirculating ducts when the ducts are located either in the upper silica masonry or in the concrete mat, the plates being clamped by the silica brick walls while still permitting the dilferential expansion of the silica.

In the second embodiment of the invention, the waste gas recirculation duct is formed by arranging fireclay tile or brick liners within the concrete mat, which tile or liner brick form hollow sections with joints between them and joints between their outer surface and the surrounding structure.

At their ends the recirculation ducts are provided with gas riser extensions leading to, and in part constituting a part of, the rich gas risers or underjet ducts, and the venturi throat of my aforesaid patents may be formed within the upper silica brickwork above the plane of the top of the concrete mat. The removable calibrated nozzle is mounted in a metal gas line which line is connected to a gas riser extension of the recirculation duct that is located within the concrete mat, the nozzle being removably connected to a part of the metal gas line which is attached to the gas riser extension and which also passes through an enlarged passage in the portion of the concrete mat below the recirculation duct. The top of the nozzle terminates in the region of juncture of the rich gas riser or underjet duct with the recirculation duct through a gas riser extension portion thereof, for jetting the gas in a manner to induce the ow of recirculated waste gas.

The metal gas line and the removable nozzle as well as the recirculation duct all being connected together within the concrete mat through a gas riser extension portion of the recirculation duct, assures proper alignment of the gas line and its nozzles, and the recirculation duct for jetting in the rich coke oven gas, since they are formed in fixed relation to a rich gas riser extension portion of the recirculation duct element in the concrete mat, and thus assures alignment of the nozzle, its gas line, the rich gas riser extension of the duct, and the recirculation duct with each other below the rest of the portions of the so-called underjets that are formed as a channel in the silica brickwork of the regenerator division walls and extend from just above the concrete mat up to the bottoms of the combustion lues.

In this second embodiment, the recirculation duct and its gas riser extensions are formed to constitute a single unitary whole movable as a unit within a free space in an upwardly open pocket in the top of the concrete mat and interconnected with the silica brickwork above the mat for movement in unison therewith.

In this embodiment, the recirculation duct and the gas riser extensions are in part formed as an upwardly open steel casting to permit lining it with reclay or liner brick. When `so lined the casting holds the entire recirculation duct and its gas riser extensions together as a unitary single entity and is located in the pocket in the concrete mat to permit the castingwith its lining to be moved with the silica masonry as a structural entity relative to the concrete of the mat which encases it.

For eecting this unitary movement, the upper parts of the gas riser extension portions of the waste gas recirculation duct casting have a part or parts which project above the plane of the top of the concrete mat into integral relation with the bottom of the silica brickwork above the mat that contains the rest of the rich gas riser underjet.

With this form of the invention, the rich gas nozzles and their gas lines are interconnected as a single structural unitary whole with the recirculation duct, for simultaneous movement of them together in unison with the silica brickwork.

In this manner the rich gas nozzles and waste gas riser extensions and the rest of the recirculation duct structure are interconnected to the silica brickwork to simultaneously partake of the movement of the silica brickwork in its expansion and contraction. Thus, as the silica expands and contracts, the rich gas nozzles, their gas lines, and the recirculation duct units therefor, 4also simultaneously move in unison therewith relative to the concrete mat in which the recirculation duct and the rich gas nozzles are contained, and thus are kept in alignment with the rest lof the underjets in the upper portion of the silica walls above the mat under all movement of the walls containing the rest of the underjets that lead up to the bottoms of the combustion ues. The removable rich gas nozzle and its pipe line are tixedly connected to an orice member formed in `a rich gas riser extension portion of the recirculation duct element, for their movement together as a single unitary whole with the silica brick wall above relative to the concrete mat and to the reclay lining of the regenerator sole channels which expand less than the silica.

With this embodiment of the invention, the venturi throat is omitted in some instances, and in some instances is formed as `an integral part of the portion of the rich gas riser underjet duct that is formed as a vertical channel in the :brickwork of the silica regenerator division wall above.

Thus, the recirculation duct, the venturi throat, when used, and the removable gas jetting nozzle are kept in coaxial valignment, not only with each other but also with the rest of the rich gas riser ducts under all the movements of the silica brickwork relative to the concrete mat and the regenerator sole channels, as the rich gas nozzle is in my aforementioned Patent 2,507,554, since the recirculation duct is now integrated for movement in unison with lall the other foregoing elements and with the silica regenerator division walls relative to the concrete mat and to the clay bri-ck of the on and off regenerator sole flues, and the metal leakage-proof plate `serves to prevent leakage from the sole fl es into such a recirculation duct system when movably mounted directly below the sole flues in kan upwardly open pocket in the concrete mat. This permits the sole flues to be disposed lower down on top of the mat while having the reciroulating duct system contained movably in gas tight relation in an upwardly open pocket in the top of the mat directly under the sole channels.

In the form of the invention in which the recirculation duct, when located in the concrete mat, is xedly interconnected with the silica brickwork of the regenerator -areas-a2 division walls, the leakage-proof plate is not overlapped lengthwise" of A the Yregenerators but extends under the karea yof the .soleI ues only/immediately over-the recircula- -ti-on duct areas therebeneath.

It will be understoodhowever, that the feature of interconnecting the rich-gas.risers-removable gas inlet nozzle, and recirculation duct, when-located in the concrete mat, .Jvith the. silica brickwork of the regenerator vdivision walls :for movement in'unison is not limited in all -its aspects t-o joints, ysince .muchuof the advantages of such keying or interlocking, or interconnection-feature Vmay be attained, although in a-lessuadvantageous way, without employing or requiring the leakage-proof featureto be lused therewith` in -all instances.

`In Aaddition-tothe general objects recited above, the invention has -t'or furtherA objects such other improve- -ments rand advantages in construction and in operation as ,".maybe fou-nd to 'obtain inthe structurehercinafter described or claimed.

E1n the accompanying ydrawing forming -a part of this specification and showing for purposes of exempliication a preferred apparatus and method in which the invention maybe embodied and practiced but Without limiting the claimed Iinvention in all its aspects to such illustrative in- *stance or instances.

Y Figure lis a vertical sectional view of a part of an underjet coke loven battery, taken longitudinally of the -:battery, that is,transverse1y.of the length of itscoking chambers, and illustrating the preferred embodiment-'of the present invention.

FigurelZ is` a vertical sectional view -of the same taken at right angle to the section of Figure 1, that is, crosswise of the battery, longitudinally of the length of its `coking chambers.

Figure 3-is an enlarged detail View in vertical cross- .section-lengthwise of the Ybattery Ishowing the relationship between the metal joint-intercepting plate and the sole channels of the regenerators and the top of the recirculation duct.,

Figure 4 is` a vertical sectional yiewv illustrating a secondvembodim-ent of the present invention, the view illus- .trati'ng a modiiied form lof the construction 'illustrated in Figure .l, to incorporate the second embodiment 4of the invention, with the recirculation duct interconnected with the silica brick of the regenerator Vdivision walls, for vmovement in vunison therewithrelative to the concrete mat, and 4the rich gas nozzles connected with the duct to movel together as a unit therewith in the region of the concrete mat; the views illustrating a structure Yin which the venturi throat is omitted, but may be employed, as indicated in dotted lines.

lFigure-5 is a Ytop plan View on line 5--5 of 'Figures 4 and-6. A

--Figure 6A is a vertical cross-sectional view of VFigure 4, the view being taken aty ri'ghtuangles'A to Figure 4, crosswise of the battery, thatis longitudinally of `the coking chambers and heating walls.l 'l 'Y Figures 7 and 8 are views similartoFigures 4 and 6, illustratinganother form of interconnecting the richl gas nozzles with the underjet duct for theirmovement as a single unitary whole with the regenerator division walls but with the discharge end `of thenozzle 'located above the concrete mat for discharge into a venturi `throatulo- A:cated in the region of the silicabrickwork of thenregenerator division walls.

Figure 9 is a top planview `on line .9 9 .of Figure 7.

VFigure 1.0 is Y'a vertical cross-sectional view on line 1 0-,L10 `of Figure 7.

Y The same icharacters of reference indicate the same parts throughout the several views.

The novel features of the invention are incorporated in cross-regenerative cross-overdue interconnected vertically :flued by-.productcr chemical recovery coke Loven vot Athe .ztype of I. BeckertPatent No. 2,100,762, and for conuselentirely Awith the leakage-proof plates for intercepting venience the present invention will be onined to applicatidnkof the invention.' The features of thefinvention are, however, readily susceptible for other uses,'for example in connection with coke oven-*batteries` of 'other forms, such as twin or rhairpin'ue types of underjet ovens, and other Itypes of underjet ovens employing on and loit combustion hues, regenerators, and underjets, hence it is manifest thatthe scope ofthe invention is nothcondined in all its :aspects solely tothe specific use and Aspecitic embodiments herein described.

rheheating of the-coke ovenbatteries isa continuous process which is carried-out in two-halves ofha cycle.

` In .one half of the-cycle-ther heating ues. are-heatedvby combustion, the heating flues, regenerators, and rich gas Afeed conduits are termed on combustionnues, regenerators, and-rich gas conduits, andwhen operablefor outflow of combustion, the term off is used.

The heating `hues, regenerators, and richgas conduits of said batteries are operatively disposed in two sets, for concurrent on" and off flow. AIn one half ofY thecycle, lone set ofheatingues, and their air and gas supply mechanism serve for on ow, while the other set of lheating Vilues and -their regenerators servefor y olcf flow concurrently of the-waste gases of combustion from the first set. On reversal, for the next half of the lheating cycle,

the'forrneru oi -iow set becomes theon flow ,set yfor combustion, and the-former -onflow set becomes the off low set fornexhaust of the combustion gases.

vFor this, -the combustion ues are connected at their upper parts for passage of the combustion products from the ues of one setl -to theuves of the .other set in alternation, as shown in Figs.-l and 2.

-Referring to the drawings, thevertical combustion ilues are connected by cross-over conduits 24 into two sets12,

A14,- forvconcurrenton and oil `tlow. Each flue 12, 14,

is connected with apairrofcross-regenerators, the lflue 12, with an air regenerator 1S and a gas regenerator f16, and *thel ues-14 are connected with an air Yregenerator 20 and agas regenerator 22. The-regenerators 1.8, 20, serve the vlues of a single heating wall'individually, whereas the wide intermediate regenerators 16, -22individually serve in common the ues of two adjacent heating walls,

Likewise, the flues12 of one set kareserved` individually by individual rich' gas riser conduits or underjetsg26,

whereas the fiues `14 of the 'other set are served individually by individual rich ygas risers or underjets26'.

The regenerators vcommunicateby regenerator ducts and outlet ports 25 with the bottoms of the individual combustion flues, and the rich gas risers 26, 26 extend upwardlyl to the bottoms of the combustion ilues through the silica brickworkA of the regenerator division walls l25 which also are pillar walls thatsupport the upper masonry -mass of silica brickwork, constituting the coking chambers 1t! and vertically flued heating walls. At their lower ends the rich gas risers-26, 26 extend down into communication with the nozzlesy 30 -of the underjet ducts, which nozzles arelremovablymounted in metal conduitsSZvof the gas line, which are connected to headers 50, by means of exible tubing 4 8, all Vof vwhich are ,accessible to-an attendant moving yaboutin the basement space underneath the concrete mat 38.

Referring to the embodiment illustrated in VFigsfl to 3, for recirculation of waste gas into admixture ywith the rrich gas when it flows into an on rich gas riser, the on and lorich gas risers are interconnected with-eachother channels 36 of on and ofi regenerators that are located between those rich gas riser ducts 26, 26 which are interconnected by duct 34.

In this embodiment the duct 34 is located in silica brickwork above the concrete mat 38 and the rich gas n'sers are provided with a venturi throat 28 which forms a part of an aspirating mixer.

The nozzles terminate below this throat 23 and at the juncture of the rich gas riser with the duct 34, so that discharge of gas from the nozzles 34] induces a ow of Waste gas from an off combustion iiue, down through its oli rich gas riser, through the duct 34 into mixture with the gas being jetted from the nozzles 30, for dilution of that gas as it rises in the ducts 26, 26', before the rich gas discharges into the bottoms of the combustion tlues 12, 14.

In this embodiment of the invention, the sole channels 36 are formed of clay brick, whereas the regenerator pillar-division walls 25 are composed or" silica brickwork. It is necessary to provide silica brick between the bottoms of the clay brick sole channels 36 and the concrete of the oven mat 38, for equal expansion and alignment of the recirculation duct 34 with the portions of the rich gas risers in the silica division walls. Because of the greater differential in expansion of silica as compared with the concrete of the oven mat and the clay of the brick of the sole channel, the walls 25 are mounted on the mat 38 to permit their longitudinal movement, under expansion, relative to the mat. It is also necessary to provide expansion joints 40 for the transverse expansion (Fig. 3) movement of the silica brick ll 41 between the clay bottoms 36 of the sole channels 36 and the top of the concrete mat 3S, to accommodate expansion lengthwise of the ducts 34, all as more particularly pointed out in my aforesaid Patent 2,507,554, which is hereby made a descriptive part hereof. Said joints 40 must extend down from the bottom 36 of the sole channels 36 to the top of the concrete mat 38.

The principal expansion of the oven structure and heating walls especially takes place when the oven battery is heated from a cold condition to a hot operating condition. Some different expansion and contraction also takes place when the operating temperature is materially changed for coking different types of coal in the chambers 10. The mortar joints between the bricks of walls 25', 4l, are normally iilled, but may, in time, develop iissures, allowing of some leakage under the pressure differential conditions. The weight of the upper masonry mass on the regenerator pillar-division walls 25 insures suiiicient gas-tightness of the bottoms of those walls 25 with the top of the concrete mat 38, to prevent leakage through the expansion joint between them.

The expansion joints 40 normally close up, when the battery is heated up, and thus prevent leakage therethrough. However, in the course of time, it is possible that somewhere in the battery some of these numerous mortar joints, and expansion joints 40, may open up suiciently for some air to leak from an on sole channel 36 above into the recirculation ducts 34, causing a small amount of air to mix with the rich gas issuing from an on jet 30, which might result in less uniformity in heating of the coking chambers.

In accordance with the present invention, to the end of further insuring against such leakage, metal jointintercepting plates, plates 52 as I have above described, are laid on the brickwork 41, during the course of erection of the oven battery, in the horizontal plane of the area between the bottoms 36 of the sole channels 36 and the top S4 of the recirculation duct 34.

As shown in Figs. l to 3, the top 54 of the duct 34 is contiguous to the bottom 36 of the sole channels 36 and the plates 52 are laid on the top 54 so as to lie in the joints 53 between the bottoms 36 of the sole channels 36 for the regenerators and the top 54 of the recirculation duct 34.

Preferably the sole channels 36 are formed of special linings 36 laidl within the regenerator bottoms and the plates 52 are interposed between the bottom clay liner 36 and the silica brickwork 41 therebeneath.

These plates S2 extend from side to side of the regenerator chamber area at the bottoms of the regenerators to at least the side surfaces of the adjacent pillar walls 25' and preferably extend at their sides into the joints of the brickwork in the pillar walls 25 to prevent leakage from the sole ues 36 into the recirculating ducts 34.

These plates 52 are, in the embodiment of Figs. l-3, in sections lengthwise of the heating walls and coking chambers 10, and so are overlapped in end-to-end relation as at 52'.

Preferably they are of the now conventional stainless steel, and No. 24 gauge, type 302, although other gas impervious material also may be used which is of a composition capable of withstanding the temperatures and abrasion due to repeated expansion and contraction, of this region of these now conventional ovens, without deterioration during the normal expected life of this region of such batteries.

In the embodiment illustrated in Figs. 4 to l0, the recirculation ducts 34 are located in the concrete of the oven mat 38. In this embodiment, the mat 38 is formed with pockets 55 to receive the recirculation duct 34 in the form of precast fire-clay conduit members or liner brick, each duct 34 having gas riser extensions 5S at its opposite ends.

As shown in all Figures 4 to l0, the ducts 34 are connected with the rich gas risers 26, 26 of a plurality of combustion tlues, so that each recirculation duct 34 serves in common two off and two on underjet ducts.

In the form of the embodiment illustrated in Figs. 4 to 10, the waste gas recirculation conduit 34 is formed by locating in upwardly open pockets 55 in the concrete mat, precast iireclay tubular sections or liner brick 56, of rectangular contour in cross-section on their inner tubular portion, and of rectangular contour in crosssection on their outer portions. The tubular duct 34 is formed `of pre-cast fire-clay sections or liner brick 56 with joints 57, Figs. 8, l0. These sections or brick are Wholly located in the concrete pocket 5S, and terminate at their upper parts in the plane of the top 59 of the upper portion of the concrete mat 38.

The silica lill 41 as in Figs. 1 3, is omitted from beneath the on and oit sole ues of the on and off regenerators. The lire-clay liner-brick 36' for the sole tiue or channel 36 are then laid lower down immediately on the top 59 of the concrete of the mat 38 but with the metal plates 52 in between.

The venturi throat 28 is located above the gas riser extension 5S of the duct 34 in the portion of the underjet ducts in the silica Walls above the plane of the top 59 of the concrete mat 38. The duct 34 is also provided at each end with an orifice member 60 for connection of the meal gas lines 32 for the vertical ues served by the underjet ducts 26, 26' that the recirculation duct 34 serves. The removable calibrated nozzles 30 are contained in these lines, with the nozzle projecting into the juncture of the recirculation duct 34 with the rich gas risers or underjets, the nozzle extending through the orifice member 60 for the line 32. The nozzle 30 is removably connected in an orice member 61 in the line 32; members 58, 60, 61 also constitute a part of the gas underjets 26, 26.

In my aforesaid Patent 2,507,554, provision is made for interlocking the gas line 32 and nozzles 30, with the silica brick of the structure 2S' that is differentially expansible on top of the concrete mat 38, by means of metal blocks 42 in cement 43 in recesses 67 in the base of the silica walls 2S', to move the nozzle 30 in correspondence with the movement of the silica brickwork 25', during its movement in expansion and contraction, relative to the concrete mat, and to the clay of the sole channel liners36f, tothereby hold..thenozzlef30and venturi throat 28 in coaxial alignrnentwitlfr each'other and with the axis of the upper.- portions of the rich gas riser ducts 26, 26', in the silica walls 25',Y as shownin Figs. l-3-ofV my present invention. l vTo this end the present invention in Figs. 4 to 10 provides the recirculation duct and' itsv gas riser extension, in part, in the form of'a pre-cast upwardly open steel castingr For this, the recirculationduct 34vand. its riserextensionsl 58v are in a multipart .form of a.10wer pre-cast metal conduit trough 63,; corresponding with a like but. longer, wider, and. deeper upwardly open pocket 55 formed .inthe top ofthe concrete. mat 38, and an. upperI fireclay liner. section. comprising;v tire-clayl linerbrickV 56, which: completes the formationy ofthefrecirculationducts 34 and their' riser extensions..58

The. pre-cast. metal. portion has upper marginal terminal extensions` 64-overlapping. in slidableriding'relation in arecess or ledge.65. in.ther.upperf part or top ofthe surrounding. concrete 'of the-.mat` 38.A

Ther. top of the. metalcastingandits fireclayliner 56 terminate inV the: same plane as the plane.59f"of. thev topl of themat-r38eon which-.ride'the silica-brickwork25- and the sole ue liner brick 36- The liner 5.6. is inthe. formof brick laid with-joints 57, Figs-,.8, 10, to form the-..fou-rA sides,top,- bottom, and' lateral wallsy of a recangular.duct-34-terminatingat each endina riser section 58..leading?upwardly'intocommunication:v with therich... gas` riser. portions -26, 26': in the silica-brick regenerator divisionwallsx25f, the. specic. structure. of they brick 56 and joints 57, although not shown, being. of conventional form.

The metal plate portion- 63v ofthev recirculationducts, likewise have, at each end of they duct 34-portion thereof, gas riser portions 58.

The.. upper tire-clayl portion-.56 andthe lower: metal castingportion 63.. together constitute a sing-le` unitary whole or entity in which the castingof metal: contains the .fire=clay portion 56- 'togetherA with i, the'metalf. casting in av manner that the entirev recirculation duct and"y its gas. riser-v extensions arey h'eld together"V as ar unitary.;7 single entity which is locatedy in-.thepocket155g inthe top of the. concretemat, so as topermit thecastin'g Witlr'its lining: to. be Ymoved, as asingleunitaryywholerela-tive tothe concrete of the mat inwhich they;arercontained,` bythe movement of thesilica brickworlc 25? ofathe-"bati tery resting on top-ofithe `concrete-mat 38'; asvit expands..

and contracts.

To this end, the gas riser extension'portionsfSS'ofcastJ ing. 63, areY provided with upperribs-66-which extendfupwardlyfrom -the top plane-.of the castingzattheaplaneof thetop of :the-concretemat to ar distancerabovefthetoplof the concrete mat 38. Theseribsor'keysfsform'fintere locks which project into thepocket, or-groovegonljointg 67 inthe bottom face of thelowenportionof the "silica' Walls 25-, as invtheicase of the. rich gas'nozzles of myfafore= said Patent 2,507,554.

These ribs `66 -serveto Vkeygand'iiix not only-'thevnozzle 30 'and gas line-132, butfalso the .recirculationzductlandy the-,riser extensions 58, to rtheeupperfsilica; brickworlci25f. for movement in unison, as afsinglerunitary'.whole,-.witlr each` other and with-the silica, ,relative-toi the:.less2ex= pansive clay ofthe sole channels andfconcreteroff the oven mat.` In thisv manner'they arei-allrheld-togetherin alignment with the gasfrisers 26; 26@y andwith eachother, and with the nozzle 30 coaxially of the throat-28;I when tlrelat-ter is also,.used, witlr.allxmoverrrentsof'thesilica brick-work- 25A above.

Intuone. form, Figs; 4s to16, the venturi throat 2813 is omitted fromthe npperzextensions SSJand-'the'rest of the rich 4gas -underjetsz` 26,' 26'; and the; nozzleI A30- Iterminates in thefconcreternat atitherlevelfoffthe duct 341. The-gas riser extensionporti'ons. 58 are'extendedfat each: endof the-duct134 in-the'form ofa-T having at' each end a gasriser outlet *58:forming`1a-fpart of therunderjets'126f 26".

Thesnozzle 30 is removably mounted integrally with tthe' duct 34 by means ora screw tlirea'ded engagement with an orice member61 secured to line 32 inscrew threaded engagement with' 60 formed in the metal of the ductc'34 and all forming a part of thev rich gas risers2'6', 26". c

Alternatively, the rich gas underiets' may be provided at their lower portions just above the top of the mat' 3,8; with a venturithroatas indicated'r in dottedlines in Fig'.v 6.

In another form, Figs. 7-10, the venturi throat 28'is formed in the upper portions of' the risers .orunderj'e'ts 26, 26 that are formed in the pillar walls 25', and more particularly are formed at a level below' the" tops"of`fther sole channels 36':

In these instances, the'nozzles'30 terminate belowsaid throat 28 but above the top` of the concrete' rat' 38.'`

In the form-shown in Figs. 7'10, the' riser extensi' iv portion 58 of the ducts'l 34'comprise averticalrdict'32Vy leading to a forked verticalduct68in`the"portion of the' silica wa11s25 between two riser ducts 26' (or'26)", which duct 681leads by forked extensions 69 to the'two risers 26 (orV 26). Thel metal Wall portions 702 of the chamber portions for the -gas riser'extension portions 58`of the'du'ct 34, Vare extended to the two risers 26' (0h26) andarethere provided with thev orifice members 60 whichl are' in align"- ment with the rich gas risers 26, 26 and form` apart thereof.

Within theV oriiice member 60 is removably mountedl integrally with theduct member 34 as a whole, the nozzle- 30 by means of screw-threaded engagement therewith.

The Waste gas recirculation chamber portion 34' ofthe gas riser extension portion 58 of the duct 34 isv confined to the width and depth of'the main portion of'` the waste gas recirculation duct 34;

In' the embodiments of Figs. 4-10, the stainless steel gas-'leakage proof plate 52 lies underneath the bottoms 36V of the'sole flue channels 36 and extends underneath the silica walls 25', lengthwise of the battery, These plates 52 extend crosswise of the battery from just in front of the ribs 66 to a point-near the Voutside edge of the flange of the trough at the opposite side of the duct 34, overlapping the joint of the top bricks 56 ofthe recirculating duct 34 with the top of the metal troughs 64-which ride in the recess thus intercepting the jointsi In this manner, as the rib 66 moves forward, toward thev sides of the oven batteryin expansion, as the walls 25 expand and the recess 67 therein moves forward relative to the concrete mat 38, and the clay liners-of the sole channels,k the leakage proof joint intercepting plates 52 move forward in unison with the wall 25', rib 66, land with the recirculation duct 34 as a whole and the rich gas nozzles 30.

In. operation, air and gas is introduced into the bottoms of the combustion fines of one set 12 whereinl the flame extends to they tops of the ues, and extinguishes as the gas passes-out into the upper ports and into the horizontal ues that discharge'the waste gas to the crossover ues 24. The latter ilues 24 pass the waste gases to the hori` zontal. flue and upper ports in the next heating wall; whence the gas passes down through the ues of the other set 14.

The ovenV battery illustrated is of the combination type. Hence, Whenfiredwith-.rich gas,such as-the coke oven gas that'thechambers 10 generate, this gas is fed in by, conduits 50, through ilexible 'conduit 48 tometalgp'ipe 32 and' nozzleffor delivery, through the throat 28"and upperpo'rtion ofthe underjets, tothe bottoms ofthe iles 12. Simultaneously, air is admittedthrough the sole channels 36'fofthe pairs of regenerators 16, 18, to the latter, which disoharge'the air vinto the bottoms of the flues-12lA The waste gases exhaust through the ilues 14 and their regenerators A2l), 22,- andI their sole channels- 36" tothe waste heat tunnel and'stack.

O11 reversal, thetlow of gas and air is stopped'tothe lconduitsr50 and to the sole. channels Afor the'regenerators 16', 18, for the set of ilues 12, and turned -on into thecon# arsosa 11 duits 50 and sole channels for the regenerators 20, 22, for the set of flues 14. f

When underiiring with lean gas, such as producer gas or blast furnace gas, the conduits 50 are disconnected so that rich gas is not fed in through line 32 to the underjet ducts 30, 26, 26. Instead, the wide regenerators 16, 22, are connected with a supply of lean gas, so that lean gas is fed on one half of the cycle by regenerators 16 and through the other regenerators 22 in the next cycle to the flues 12 and 14 in off and on operation simultane ously with the olf and on operation of the regenerators 18, 20 for feed of air,

However, in the event the lean gas has such a low B. t. u. value that even after preheating in the regenerators, the heat effect is still insuicient to coke the coal charges in the oven chambers 10, equivalently to rich gas or producer gas tiring, as may be the case with blast furnace gas, as is pointed out in my aforesaid Patent 2,507,554, then the mains 50, lines 32 and underjet ducts, 30, 26, 26', are

also employed in on and oit operation, in correspondence with the operation of the regenerators 16 and 22 for inflow of lean gas, to enrich the lean gas, such as blast furnace gas, in the bottoms of the ues l2, 14, as it is fed in by the regenerators 16 and 22, in alternation.

When the rich gas is fed in by the nozzles 30, in rich gas underring, and in enriching during lean gas underiiring, the jet of rich gas, as it issues from the nozzle into Ithe rich gas riser portions in the region of their juncture with the recirculating ducts as by the gas riser extensions thereof, and below the throats 28 when they are also used, aspirates waste gas from the bottoms of the oit operating combustion ilues, down through their off rich gas risers, and through the recirculation ducts, into admixturevwith the rich gas being jetted in through the on nozzles 30, whence the mixture flows up through the on rich gas risers or underjet ducts 26, 26', into the bottoms of the vertical combustion ilues l2, 14, then operable for on ilow.

The jet nozzles 3), for the individual flues are calibrated to introduce the proportionate amount of rich gas as required among the several fines, in rich gas underfiring, and likewise calibrated also for delivering minor enriching portions of such gas, when regeneratively underring with lean gas enriched with rich gas.

Thus, the velocity of How of such calibrated amounts of rich gas also serves, with or without the throats 28, to control. the amount of waste gas that is recirculated to get a given predetermined heating effect in the combustion ues, all to the end of attaining uniformity in heating of the coke oven charges.

The leakage proof plates SZ insure the successful attainment of these ends, in all the described forms of the invention, since, should leaks develop in the region betveen thc sole channels 36 and the recirculation ducts 34, the plates 52 prevent the suction action of the jet at 30 from reaching the sole channels 36, and thus prevent air, when liowing in through the sole channels to the regenerators, from oy-passing the on regenerators and flowing instead into mixture with the gas from the nozzles 30 in the recirculation duct, whence it could act to vary the heat intensity in the various llues l2, 14.

The plates 52 serve a like utility when the nozzles 30 are replaced by like nozzles calibrated and substituted for enriching lean gas since, in event of air leakage into the recirculation ducts, the uncontrolled dilution of the minor enriching portions of rich gas, might result in less uniformity of heating as a result of dilution rather than in uniform enriching of the lean gas from the regenerators.

These plates 52 cut through or intercept the path of ow of air or gas from the sole channel 36 to the recirculation ducts 34, through the expansion joints 4t) or any fissures that may arise in the mortar joints of Figs. 1 3, or in the fire-clay liner joints located in the concrete mat 38 in Figs,

, 12 4l0, while still permitting the differential movement of silica to take place relative to the clay and concrete.

While the leakage plates 52 are of especial utility 1n connection with the structure illustrated in Figs. 4 to l0, in insuring against leakage into the ducts 34 by reason of their multipart construction and their shiftable disposition in the concrete mat immediately under the regenerator sole channels, when located in the pocket S5 previously formed for this purpose in the concrete mat, the features of the interconnection with the silica, as in Figs. 4-10, are not limited in all aspects to utility in use with the plate 52, since the feature of interlocking the recirculation duct, when located in the concrete mat, with the silica brickwork 25 for movement in unison therewith and with the gas risers 26, 26', the venturi throat 28, when it is employed, the nozzles 30, and all as a unitary whole, is of utility also in other relations than in relation with such leakage proof plate 52. Hence, the structure of Figs. 4 to 10 is not limited in all its aspects to use only with the gas-leakage proof features thereof.

The invention as hereinabove set forth is embodied in particular forms and manners, but may be variously embodied within the scope of the claims hereinafter made.

I claim:

1. A regenerative coke oven, comprising: a silica brickwork masonry mass constituted of horizontal coking chambers alternating in position side-by-side with tlued heating walls, regenerators separated by oven supporting regenerator division walls located below the coking chambers and heating walls, clay brick sole channels below the regenerators, a concrete oven supporting mat above an accessible basement space beneath the mat, said regenerator division walls resting directly on the concrete of the top of the mat and being constituted of silica brickwork masonry where they rest on the concrete of the mat, and said clay brick sole channels being laid intermediate the silica masonry of the adjacent regenerator division walls and also resting directly on the concrete of the top of the mat, on and off rich gas risers extending upwardly through the concrete mat and through the silica masonry of the regenerator division walls into communication with the ues of the heating walls, waste gas recirculation ducts slidably disposed in pockets within the concrete mat and provided with gas riser extensions also located within the concrete mat for communicable connection as a part of the off and on gas risers in the regenerator division walls, said gas riser extensions being tixedly interconnected with the silica masonry of the bottoms of the regenerator division walls for movement in unison with each other relative to the concrete oven-mat and the clay sole channels, and said gas riser extensions and the rest of their recirculation ducts comprising a multipart construction innerlined with refractory and detachably secured together, as a single unitary whole, for movement relative to the concrete mat and the clay brick of the sole channels, with movement of the silica of the regenerator division walls, rich gas inlet nozzles removably fixed in the gas riser extensions and disposed therein to discharge rich gas in the form of a jet in the region of juncture of the recirculation ducts with the rich gas risers and coaxially of the latter, and metal joint intercepting plates interposed in a horizontal plane between the concrete of the top of the concrete mat and the clay and silica bottoms of the clay brick sole channels and silica brick regenerator division walls, to prevent leakage from the sole ilues into the recirculation ducts.

2. A coking retort oven as claimed in claim l, and in which the outlets of the rich gas inlet nozzles are disposed in the gas riser extensions of the recirculation ducts within the portions of the rich gas risers in the region of the concrete mat below the bottoms of the silica brickwork.

3. Apparatus as claimed in claim l, and in which the recirculation duct and pocket construction comprises an upwardly open pocket for the recirculation duct and a lower upwardly open pan having an upper lining of liner brick to form the recirculating duct passage, said pan having the riser extension portions to which the gas inlet nozzles are attached and having pan portions in overlapping relation with the concrete of the mat for sliding relation therewith.

4. A regenerative coke oven, comprising: a silica brickwork masonry mass constituted of horizontal coking chambers alternating in position side-by-side with flued heating walls, regenerators separated by oven supporting regenerator division walls located below the coking chambers and heating walls, clay brick sole channels below the regenerators, a concrete oven supporting mat above an accessible basement space beneath the mat, said regenerator .division walls resting directly on the concrete of the top of the mat and being constituted of silica brickwork masonry where they rest on the concrete of the mat, and said clay brick sole channels being laid intermediate the silica masonry of the adjacent regenerator division walls and also resting directly on the concrete of the top of the mat, on and off rich gas risers extending upwardly through the concrete mat and through the silica masonry of the regenerator division walls into communication with the iiues of the heating walls, waste gas recirculation ducts slidably disposed in pockets within the concrete mat and each provided at each end with waste gas duct branches terminating in gas riser extensions also located within the concrete mat for communicable connection as a part of the off and on gas risers in the regenerator division walls, rich gas inlet nozzles removably fixed in the gas riser extension and disposed therein to discharge rich gas in the form of a jet in the region of juncture of the recirculation ducts with the rich gas risers and coaxially of the latter, the gas riser extensions of the waste gas recirculation ducts being iixedly interconnected with the silica masonry of the bottoms of the regenerator division walls for movement of the nozzles, riser extension and the rest of the recirculation ducts in unison relative to the concrete oven-mat and the clay sole channels, said gas riser extensions and the rest of their recirculation ducts comprising a multipart construction inner-lined with refractory-material and detachably secured together, as a single unitary whole, for movement relative to the concrete mat and the clay brick of the sole channels, with movement of the silica of the regenerator division walls, and said rich gas inlet nozzles being located within the structure so as to have their outlets in the region of the silica brickwork above the top of the concrete mat, and metal joint intercepting plates in a horizontal plane between the concrete of the top of the concrete mat and the clay and silica bottoms of the clay brick sole channels and silica brick regenerator division walls, to prevent leakage from the clay sole flues into the recirculation ducts.

5. A coking retort oven as claimed in claim 4, and in which a venturi throat is disposed Within the gas risers at a level above the outlets of the rich gas inlet nozzles.

6. A regenerative coke oven, comprising: a silica brickwork masonry mass constituted of horizontal coking chambers alternating in position side-by-side with flued heating walls, regenerators separated by oven supporting regenerator-division walls located below the coking chambers and heating walls, clay brick sole channels below the regenerators, a concrete oven supporting mat above an accessible basement space beneath the mat, said regenerator-division walls resting directly on the concrete of the top of the mat and being constituted of silica brickwork masonry where they rest on the concrete of the mat, and said clay brick sole channels being laid intermediate the silica masonry of the adjacent regenerator division Walls and also resting directly on the concrete of the top of the mat, on and off rich gas risers extending upwardly through the concrete mat and through the silica masonry heating walls, waste gas recirculation ducts slidably disposed in pockets within the concrete mat and provided each at each end with gas riser extensions on opposite sides of the `ducts which extensions are also located within the top part of the concrete mat for communicable connection as a part of the oi and on gas risers in the regenerator-division walls, rich gas inlet nozzles fixed in the gas riser extensions and disposed therein to discharge rich gas in the form of a jet into the rich gas risers and coaxially of the latter, forked extension ducts located in the silica brickwork of the regenerator division walls, each of which has a central branch which is aligned with one end of one of the recirculation ducts and has side branches leading to several gas risers at the level at which the aforesaid gas inlet nozzles discharge therein, and metal joint intercepting plates interposed in a horizontal plane between the concrete of the top of the concrete mat and the clay and silica bottoms of the clay brick sole channels and silica brick regeneratordivision walls, to prevent leakage from the clay sole iiues into the recirculation ducts.

7. A coking retort oven as claimed in claim 6, and in which a venturi throat is disposed within the gas risers at a level above the discharge ends of the branches of the forked extension duct.

References Cited in the iile of this patent UNITED STATES PATENTS 1,374,546 Becker Apr. 12, 1921 1,509,196 Dressler Sept. 23, 1924 2,098,013 Pavitt Nov. 2, 1937 2,216,983 Otto Oct. 8, 1940 2,306,678 Van Ackeren Dec. 29, 1942 2,346,991 Otto Apr. 18, 1944 2,470,112 Rueckel May 17, 1949 2,507,554 Van Ackeren May 16, 1950 2,516,929 Van Ackeren Aug. l, 1950 

1. A REGENERATIVE COKE OVEN, COMPRISING: A SILICA BRICKWORK MASONRY MASS CONSTITUTED OF HORIZONTAL COKING CHAMBERS ALTERNATING IN POSTION SIDE-BY-SIDE WITH FLUED HEATING WALLS, REGENERATORS SEPARATED BY OVEN SUPPORTING REGENERATOR DIVISION WALLS LOCATED BELOW THE COKING CHAMBERS AND HEATING WALLS, CLAY BRICK SOLE CHANNELS BELOW THE REGENERATORS, A CONCRETE OVEN SUPPORTING MAT ABOVE AN ACCESSIBLE BASEMENT SPACE BENEATH THE MAT, SAID REGENERATOR DIVISION WALLS RESTING DIRECTLY ON THE CONCRETE OF THE TOP OF THE MAT AND BEING CONSTITUTED OF SILICA BRICKWORK MASONRY WHERE THEY REST ON THE CONCRETE OF THE SAID CLAY BRICK SOLE CHANNELS BEING LAID INTERMEDIATE THE SILICA MASONRY OF THE ADJACENT REGEERATOR DIVISION WALLS AND ALSO RESTING DIRECTLY ON THE CONCRETE OF THE TOP OF THE MAT, "ON" AND "OFF" RICH GAS RISERS EXTENDING UPWARDLY THROUGH THE CONCRETE AND THROUGH THE SILICA MASONRY OF THE REGENERATOR DIVISION WALLS INTO COMMUNICATION WITH THE FLUES OF THE HEATING WALLS, WASTE GAS RECIRCULAATION DUCTS SLIDABLE DISPOSED IN POCKETS WITHIN THE CONCRETE MAT AND PROVIDED WITH GAS RISER EXTENSIONS ALSO LOCATED WITHIN THE CONCRETE MAT FOR COMMUNICABLE CONNECTION AS A PART OF THE OFF AND ON GAS RISERS IN THE REGENERATOR DIVISION WALLS, SAID GAS RISER EXTENSIONS BEING FIXEDLY INTERCONNECTED WITH THE SILICA MASONTY OF THE BOTTOMS OF THE REGENERATOR DIVISION WALLS FOR MOVEMENTS IN UNISON WITH EACH OTHER RELATIVE TO THE CONCRETE OVEN-MAT AND THE CLAY SOLE CHANNELS, AND SAID GAS RISER EXTENSIONS AND THE REST OF THEIR RECIRCULATION DUCTS COMPRISING A MULTIPART CONSTRUCTION INNERLINED WITH REFACTORY AND DETACHABLE SECURED TOGETHER, AS A SINGLE UNITARY WHOLE, FOR MOVEMENTS RELATIVE TO THE CONCRETE MAT AND THE CLAY BRICK OF THE SOLE CHANNELS, WITH MOVEMENT OF THE SILICA OF THE REGENERATOR DIVISION WALLS, RICH GAS INLET NOZZLES REMOVEABLE FIXED IN THE GAS RISER EXTENSIONS AND DISPOSED THEREIN TO DISCHARGED RICH GAS IN THE FORM OF A JET IN THE REGION OF JUNCTURE OF THE RECIRCULATION DUCTS WITH RICH GAS RISERS AND COAXIALLY OF THE LATTER, AND METAL JOINT INTERCEPTING PLATES INTERPOSED IN A HORIZONTAL PLANE BETWEEN THE CONCRETE OF THE TOP OF THE CONCRETE MAT AND THE CLAY AND SILICA BOTTOMS OF THE CLAY BRICK SOLE CHANNELS AND SILICA BRICK REGENERATOR DIVISION WALLS, TO PREVENT LEAKAGE FROM THE SOLE FLUES INTO THE RECIRCULATION DUCTS. 